1. Field of the Invention
The present invention relates to a method of enantioselective addition to imines and, more particularly, to a method of enantioselective addition of organozinc to imines using a chiral β-amino alcohol.
2. Description of Related Art
Most of isolated natural products have specific stereochemistry. Most of the time, various stereoconfiguration of compounds also causes significant difference in bioactivity. Particularly, stereoconfiguration is critical for most medical compounds or drugs. For example, thalidomide, a chiral molecule, is used for treating sickness and faintness of pregnant women, but the enantiomer thereof causes abnormal fetal development. Furthermore, S, S-isomer of captopril is effective for treatment of hypertension and heart disease. In addition, S-isomer of Dopa can be used for treatment of Parkinson's disease, but R-isomer thereof has toxicity. The U.S. Food and Drug Administration, in 1992, issued an instruction that optical isomers of the medical compounds having chiral center(s) should be isolated from each other, studied separately for their bioactivity, and taken for clinical testing respectively. Moreover, only the therapeutically active isomer of the optical isomers can be brought to market. Accordingly, many scientists focus their research on the improvement of enantioselectivity to obtain substances having specific stereoconfiguration. According to these research results, it is known that the enantioselect ivity of products may be enhanced by the application of chiral reagents, chiral auxiliaries, or chiral catalysts. Through the assistance of the chiral compounds illustrated above, products of high enantioselectivity with high purity can be synthesized.
It is known that chiral amines play important roles in the synthesis of bioactive substances and medical compounds. For example, methoxyphenamine is a β-adrenergic receptor agonist and can be used to treat asthma; rivastigmine is a pseudo-irreversible inhibitor of cholinesterase and can be used to treat Alzheimer's disease; tamsulosin is a selective α1-adrenoceptor antagonist and can be used to decrease urinary symptoms caused by prostate hypertrophy; and repaglinide can stimulate the release of insulin from the pancreas to reduce blood glucose and thus can be used in treating type II diabetes.

Accordingly, it is an important object of the present invention to develop a method for preparing amine products in high optical purity.